2021_Book_TextbookOfPatientSafetyAndClin

22 Patient Safety in Radiology
CA and in case of reduction of renal function
temporary discontinuation of metformin is
recommended.
22.4.3 Safe Injection of Contrast
Agents
The injection of CA either by hand or by power
injector can cause complications following contrast
extravasation or air embolism. The health
care professional performing the injection has to
evaluate intravenous access, verify the catheter
size, monitor the flow rate of injection, and adjust
the power injector carefully for preventing the
potential adverse events [35, 36].
22.4.4 Allergy-Like and Chemotoxic
Reactions
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These adverse reactions can occur following
intravascular administration of any group of CA,
specially iodinated CA and GBCA [35]. Most of
these reactions are acute and occur in the first
hour after contrast administration (many in the
first 5 min), but in rare cases, there are delayed
reactions after injection of iodinated CA [36].
The acute adverse events can be chemotoxic
or allergy-like (idiosyncratic) reactions. They are
classified into three severity categories: mild,
moderate, and severe. Most of the acute adverse
reactions are mild, but severe life-threatening
reactions can rarely occur. Chemotoxic reactions
are related to molecular and chemical characteristics
and are frequently dose and concentration
related. Vasovagal reactions and cardiovascular
effects (especially in patients with underlying
cardiac disease) and symptoms of warmth, metallic
taste, and nausea/vomiting are examples of
chemotoxic reactions [36]. Allergy-like reactions
are independent of dose. The symptoms can
include urticaria, pruritus, cutaneous edema, or
rare anaphylactic reaction. The most important
risk factor for an acute adverse reaction to CA is
a previous reaction, and a prophylactic corticosteroid
injection is indicated. A history of asthma
and atopy can result in a mildly increased risk of
acute adverse reactions [35]. The other risk factors
include more massive doses, increased rate
of administration, the use of higher osmolar nonionic
CA, and intra-arterial (vs. intravenous)
administration [37]. The properties of GBCA that
increase the risk of acute allergic reactions are
ionicity, protein binding, and having a macrocyclic
structure [38].
The considerations required for ensuring the
minimal contrast-related acute adverse events
and their proper management are:
• providing enough education and training of
the health professionals involved in CA side
effects, their risk factors, and treatment
• screening the patients for detecting possible
risk factors
• using nonionic CA whenever possible
• considering premedication in high-risk
patients
• ensuring the availability of emergency and
resuscitation equipment
• monitoring the patients and providing accessible
communication between them and the
radiology staff before, during, and
after the injection [37, 39].
22.4.5 Adverse Events Related
to Iodinated Contrast Agents
Nephrotoxicity: Iodinated contrast agents (ICA)
can cause acute kidney injury or worsen preexisting
chronic kidney disease [40]. This effect
is known as contrast-induced nephropathy (CIN).
However, post-contrast acute kidney injury
(PC-AKI) is a general term and describes any
sudden deterioration in renal function within 48 h
following the intravascular administration of
iodinated contrast, regardless of the cause [35].
The pathophysiology of CIN is not precisely
understood [40].
The critical risk factor is pre-existing severe
renal insufficiency (eGFR